sclass RasterBars > Animation {
  LPair<IntRange, Int> streaks;
  
  *() {}
  *(int *w, int *h, LPair<IntRange, Int> *streaks) {}
  
  void paint {
    for (streak : streaks)
      fillRect(g, 0, streak.a.start, w, l(streak.a), grayToColor(streak.b));
  }
}